1. Field of the Invention
The invention relates to a vehicle wheel with a one piece rim and a tubeless pneumatic tire, which is suitable for use in an emergency roll, as well as a process for mounting a pneumatic tire on a rim with an emergency rolling surface.
2. Discussion of Background Information
Tubeless vehicle pneumatic tires of a modern design are generally designed with beads on their radially interior ends of their side-walls. A carcass of radial fabrication, designed with stress supports coated in rubber extends from tire bead to tire bead. In each tire bead there is a ring-shaped, tensile, and rigid bead core made of steelxe2x80x94which is disposed concentrically to the tire axisxe2x80x94in which the carcass is stayed. During the mounting of the vehicle pneumatic tire on the rim, the vehicle pneumatic tire is affixed with its bead on the radially exterior shell of the rim. The high tensile strength and rigidness of the bead, which is effected by the tensile strength and rigidness of the bead core, secures the scaling in the rim-tire connection desired in tubeless tires and secures the scaled seating of the tire on the rim in the inflated condition of the tire. The rigid, tensile design of the bead core hindersxe2x80x94even during demanding driving maneuversxe2x80x94an axial stripping-off of the vehicle wheel from the rim over the wheel flange, which is oriented radially outward.
For mounting or dismounting of the vehicle pneumatic tire, the tensile, rigid bead of a one-piece rim must be moved with its inner diameter over the larger outer diameter (as opposed to the inner diameter of the rigid bead) of the wheel flange. To make this possible, additional expenditure, for example, the manufacture of the rim with a drop base, is required.
If a loss of air pressure occurs, the tire side-wall buckles. It can thereby be pressed on the wheel flange, which is designed for the axial securing of the vehicle pneumatic tire on the rim. If the vehicle continues to be driven, the tire side wall and the wheel flange can be destroyed. The vehicle pneumatic tire can break away from the rim.
In an attempt to prevent the foregoing situation and to make possible a safe, continued journey, despite a loss of air pressure, it was recommended that the rim be designed with additional emergency rolling surfaces that project radially over the wheel flange on the radially exterior side of the one-piece rim, upon which the vehicle pneumatic tire supports itself with its radially inner side of its rolling surface area in the event of a loss of air pressure and which thus guarantees emergency rolling characteristics after a loss of air pressure. The mounting and dismounting of vehicle pneumatic tires on such rims prove difficult, since the tensile, rigid beads must be displaced over the even larger outer diameter of the emergency rolling surfaces, and since the emergency rolling surfaces additionally restrict the axial space between the bead seat areas on the rims which are to be used as a mounting aid, for example, the fabrication of a drop base. To be able to mount the rigid, tensile bead, the practical ratio between the outer diameter of the emergency rolling surface to the inner diameter of the tensile, rigid bead is very limited. The outer diameter of the emergency rolling surface may only be so great that the rigid bead can still be moved over it. As a result, the emergency rolling surfaces are determined in large part by a comparatively small inner diameter of the rigid bead and, thus, by a parameter which is insignificant for the emergency rolling characteristics. Vehicle pneumatic tires can no longer be mounted when the outer diameter of the emergency rolling surfaces of the rims exceeds that which is suited for optimal emergency rolling characteristics.
It is known from CTS (Continental Tire System) tires to support tubeless vehicle pneumatic tires with their beads on support surfaces on the radially inner side of the one-piece CTS rim designed with emergency rolling surfaces on its radially external side. In each tire bead there is a ring-shaped, pressure-rigid, and tensile bead core made of steelxe2x80x94disposed concentrically to the tire axisxe2x80x94,in which the carcass is stayed. With the mounting of the vehicle pneumatic tire on the rim, the CTS vehicle pneumatic tire is affixed with its bead on the radially interior shell of the rim. The high tensile strength and pressure rigidity of the bead, which is effected by the tensile strength and pressure rigidness of the bead core, secures the sealing in the rim-tire connection that is desired with tubeless tires and secures the sealed seating of the tire on the rim in the inflated condition of the tire. The pressure-rigid, tensile fabrication of the bead core hindersxe2x80x94even during demanding driving maneuversxe2x80x94an axial stripping-off of the vehicle wheel from the rim over the wheel flange, which is oriented radially inward on the radially inner side of the rim. Such a tire is known, for example, from DE-30 00 428 C2.
Since the rim seating and the wheel flange are designed on the radially inner side of the rim, a CTS tire provides a greater axial extension area for the formation of emergency rolling surfaces on the radially exterior shell of the rim than is the case with the tire-wheel system that is conventionally affixed on the radially exterior shell of a rim. On the radially exterior side of the CTS rim, the wheel flange no longer constitutes a wheel flange element which interferes with the emergency rolling.
To mount or dismount the CTS vehicle pneumatic tire, the tensile, pressure-rigid bead must be moved with its inner diameter on the radially exterior shell of the rim over the larger outer diameter (as opposed to the inner diameter of the rigid bead) of the emergency rolling surfaces and on the radially inner shell of the rim over the smaller inner diameter (as opposed to the inner diameter of the rigid core). To make this possible, additional expenditure is necessary, for example, the designing of the rim with an elevated base on the radial inner shell, as well as expensive, special mounting techniques.
The mounting and dismounting of the vehicle pneumatic tires on such rims thus also proves difficult, since the tensile, pressure-rigid CTS beads must be moved over the even larger outer diameter of the emergency rolling surfaces on the radial outer side of the rim and over the smaller inner diameter (as opposed to the inner diameter of the rigid bead) on the radial inner shell of the rim. So that the mounting of the pressure-rigid, tensile bead is even possible, the practical ratio between the outer diameter of the emergency rolling surface to the inner diameter of the tensile, pressure-rigid bead is still limited, even with CTS tires. The outer diameter of the emergency rolling surface can only be of such size that the rigid bead can still be moved over it. As a result, the emergency rolling surfaces are still determined in large part by a comparatively small diameter of the rigid bead and, thus, by a parameter which is insignificant for the emergency rolling characteristics, even with CTS tires. Vehicle pneumatic tires with their rigid beads can no longer be mounted when the outer diameter of the emergency rolling surfaces of the rim exceeds that which is suited for optimal emergency rolling characteristics.
A vehicle wheel with a one-piece rim and a tubeless, beadless pneumatic tire is known from DE 19530939 C1, in which the radially exterior shell of the rim is designed with emergency rolling surfaces. The beadless vehicle pneumatic tire is scorched on the radially interior shell of the rim. The bead-free design of the vehicle pneumatic tire makes possible the manufacturing of emergency rolling surfaces which are independent of bead diameters. For the fabrication of the emergency rolling surfaces, parameters which are important for an emergency rolling can be better taken into consideration with such a vehicle pneumatic tire, so that desired, greater diameters of the emergency rolling surfaces for the optimization of emergency rolling can be realized with ease. However, such vehicle pneumatic tires cannot be readily dismounted or exchanged without destruction.
It was recommended in DE-OS 2364274 to fasten radially a vehicle pneumatic tire with its beads between two radially spaced rim components of a multi-component rim. The bead core can elongate, so that the bead can be better mounted over the wheel flange, which is constructed on the radially exterior rim component and which is oriented radially inward, and so that, with the inner pressure of the tire, it can expand during elongation along the conical support face of the radially inner rim component. DE-OS-2364274 is not concerned with emergency rolling. The bead has great axial play between the rim components. Especially in the event of air pressure loss, the possibility cannot be excluded that the bead peels off axially and even slips out axially between the rim components. Safer emergency rolling characteristics are not guaranteed with a design of that kind.
It is known from U.S. Pat. No. 1,932,191 to fix laterally in a rim a flexible bead of a vehicle pneumatic tire with the aid of a flexible, non-metallic clamping ring constructed between the rim and bead in a circumferential groove. The flexible bead is reinforced with a core made of cloth or cords. The bead is indeed flexible, but because of the rigidity it is designed with an invariable circumferential length in the circumferential direction. The bead can thus be warped [bent] for mounting. Emergency rolling or emergency rolling problems are not known from U.S. Pat. No. 1,932,191.
The basis of the present invention is to create a vehicle wheel with a one piece rim and a tubeless pneumatic tire, which is suitable for emergency rolling, as well as a process for mounting a pneumatic tire on a rim with an emergency rolling surface, in whichxe2x80x94in an operationally secure mannerxe2x80x94the advantages of the CTS wheel-tire-system (with respect to their ability to be mounted and dismounted without being destroyed) can be added with the advantages of the bead-free, scorched wheel-tire-system with the possibility of increased optimization of the emergency rolling surfaces.
According to the present invention, a vehicle wheel is fabricated that includes an emergency rolling surface designed on the radially exterior shell of a rim, and an elastic bead to fasten the pneumatic tire on the wheel rim. The bead is enlarged on each side wall of the pneumatic tire to the inner side of the pneumatic tire and is alterable in its circumferential length. The vehicle wheel also includes a toroidal chamber, which is constructed in at least one piece in an axial front-end of the wheel rim with toroidal chamber walls, in which one which is radially interior, one which is radially exterior, one which is axially inward to the middle of the wheel rim, and one which is axially exterior to the exterior of the wheel rim. In this manner, the toroidal chamber walls which are radially inward, which are radially outward, and which are constructed axially inward to the center of the wheel rim are closed and the toroidal chamber wall, which is constructed axially outward to the front-end of the rim, is constructed closed in the radially exterior area as a wheel flange which is directed radially inward and is constructed open in its radial interior area. A filler ring is embedded in a radially secure manner inside the toroidal chamber on the radially interior toroidal chamber wall. The side wall of the tire extends inward from the axial exterior through the opening in the toroidal chamber wall constructed axially exterior and the bead is embedded in the toroidal chamber on the radial outside of the filler ring and is constructed in form-closure contact with the radially exterior, to the axially interior, and to the axially exterior closed toroidal chamber wall, so that the bead is connected to the toroidal chamber which is constructed in a single piece, to the radial exterior, to the axial exterior, to the axial interior, and to the form closure via the filler ring toward the radial interior. The bead lies completely on the filler ring especially over its entire axial extent to the radial interior and whereby especially the bead and the filler ring completely fill the toroidal chamber. Further, the invention includes a process for mounting a pneumatic tire on a wheel rim with an emergency rolling surface with a toroidal chamber, which is formed on both sides of the wheel rim in the single-piece, axial front-end of the rim. The toroidal chamber is closed radially inward, radially outward, and axially inward to the center of the wheel rim and is constructed partially open to the front-end, to embed the bead and a filler ring radially inside the bead, for fastening the pneumatic tire to the wheel rim via axial introduction through the opening. In this manner, the opening in the front-end is closed in its radially exterior area from the radial exterior by the wheel flange, which is oriented radially inward and which is formed in a single piece by the chamber walls. In this way, the tire is introduced with its bead into the toroidal chamber, which is constructed for embedding the bead and the tire then is brought with a filler ring, which is axially displaceable on the wheel rim by axial movement of the filler ring radially between a bearing surface in the toroidal chamber of the wheel rim and the bead in an axial and radial form closure to the radial exterior and axial interior to the chamber walls, to the axial exterior to the wheel flange of the toroidal chamber and to the radial interior to the filler ring and thus fastened in the toroidal chamber.
The bead core, which can be elastically altered in its circumferential length, enables the mounting of the bead by movement over the emergency rolling surface with a larger bead core diameter than in the fixed operating state of the bead and for movement over the wheel flange with a smaller bead core diameter than in a fixed operating condition, so that the design of the emergency rolling surfaces no longer need be designed in dependence upon the diameter of the bead core in operating condition and from the inner wheel flange diameter, but primarily that optimal emergency rolling characteristics can be designed accordingly. After the introduction of the bead into the toroidal chamber, the filler ring is introduced radially within the bead, axially into the toroidal chamber, so that between the radially inner toroidal chamber wall and the filler ring, between filler ring and bead, and between the bead and radially exterior toroidal chamber wall, a radial form closure is produced. Further, between the axially inner toroidal chamber wall and the bead, and between the bead and the wheel flange that forms the axially exterior toroidal chamber wall produces, an axial form closure is provided. After a loss of air pressure during vehicle wheel operationxe2x80x94during normal operations as well as emergency rolling operationsxe2x80x94a complete form closure exists axially outward and inward and radially outward and inward between a one-piece toroidal chamber of the rim and bead. Both the forces affecting the bead radially and those affecting the bead axially are thus introduced directly into the one-piece rim in the fastening area. Even during an emergency rolling operation, no significant axial forces are introduced into the only additional element, the filler ring. In this manner the bead can safely and dependably retain its position in the toroidal chamber, even during an emergency rolling operation. The bead which can be altered in its circumferential length can thus be mounted and dismounted in an easy and operationally secure manner, whereby the emergency rolling surfaces can be optimized for the emergency rolling, as can the wheel flange with respect to the axial support for the bead, as can the bead core in its operational condition with respect to its characteristics in operational condition. The force introduction into the rim is particularly secure if the bead lies completely on the filler ring over its entire axial extension radially inward. If the bead and the filler ring fill up the toroidal chamber completely, then a particularly reliable form closure between the bead and the rim is attained. By forming the vehicle pneumatic tire with elastically alterable circumferential lengths of the bead, it is particularly easy and safe to attain an alteration of circumferential length from a first circumferential length to further circumferential lengthsxe2x80x94which are individually adjusted in accordance with current demandxe2x80x94opposing the effect of restoring forces and back again in the first circumferential length by utilizing the restoring forces.
A design for attaining especially good emergency rolling characteristics is preferred, since the tread can be sufficiently supported despite the optimal spacing width of the particularly crucial shoulder regions between the tire beads of the vehicle pneumatic tire. It is particularly advantageous to design an emergency rolling surface on each of the axial side regions of the radially exterior shell of the rim, to support the shoulder regions, which are especially crucial in the event of an emergency rolling situation.
A design of the vehicle wheel is particularly advantageous in which the bead core is designed as a rubber core, integrated in the bead. The rubber core is simple to manufacture and can be stayed especially easily and reliably in the bead. The bead can hereby be designed in a simple, reliable way to be elastically expandable in its circumferential length. For a particularly secure fit, the rubber core is designed with a Shore A hardness in the range of 80 to 100xe2x80x94preferably in the range between 85 and 90.
In another embodiment of the vehicle wheel, the bead is designed completely coreless. The bead is especially simple to make, without additional expense for a core, can be modeled sufficiently elastically expandable in its circumferential length via its coreless rubber material, and can nevertheless be stayed securely and reliably by the form closure in the toroidal chamber.
Another embodiment enables a particularly simple and reliable mounting and dismounting of the vehicle pneumatic tire on the rim. After the bead has been introduced into its anchoring position in the toroidal chamber, it is displaced by a simple axial displacement of the filler ring on the bearing surfacexe2x80x94designed for this purposexe2x80x94of the toroidal chamber, into its filler position in the toroidal chamber, through which the entire form closure of the bead in the toroidal chamber is manufactured and secured. By simple, axial extraction of the filler ring from its position, the form closure is raised [neutralized, counteracted], so that the bead can be removed from the toroidal chamber and the vehicle pneumatic tire can be dismounted from the rim.
Through a further embodiment, an additional radial form closure can be attained between the side wall area, which connects directly to the bead, and wheel flange and between the side wall area, which connects directly to the bead, and the filler ring; and, thus, to the flange, at least in the penetration area through the opening. The staying of the bead in the rim hereby becomes more secure. Furthermore, the access to the filler ring from outside is thus simplified, so that mounting and dismounting, are simplified.
Through the conically expanded design of the radially exterior shell of the filler ring in its expansion outside the toroidal chamber, the tire side wall in the wheel flange area is additionally secured, and the progression of the lower tire side wall in the area adjoining in an axially exterior manner to the wheel flange is fixed with a directional component which is directed radially outwards. In this way, the form closure is additionally secured between the tire bead and the wheel rim. It is especially advantageous if the filler ring lends the tire side wall additional rigidity in the directly adjoining area on the wheel flange. In order to provide this, it is advantageousxe2x80x94in direct connection to the wheel flange axially exterior to the wheel flangexe2x80x94to design the radially exterior contour of the filler ring with a curve profile corresponding with the tire side wall contour in this area. It is preferred that the vehicle wheel be designed such that the axially exterior front end is designed as an axial support surface for the axial support of the lower tire side wall. In this manner, the tire is supported axially in the lower side-wall region to attain good handling characteristics while taking a curve and, in the event of unusual impact loads, can provide good comfort characteristics all the way to the lower side-wall region through spring deflection by neutralizing the axial support effect.
The fixing of the tire is particularly secure when the pneumatic tire is supported in the interior by the wheel rim and outside by the filler ring.
The embodiment is particularly advantageous, due to its simple fabrication, mounting, and dismounting. Furthermore, an introduction of axial forces from the bead into the filler ring is reliably prevented via the cylindrical embodiment of the radially exterior shell of the filler ring, so that the staying of the bead is even more reliable.
The design of a vehicle wheelxe2x80x94in which the largest outer diameter of the emergency rolling surfaces is a factor of between 1.05 and 1.3 greater than the inner ring diameter of the bead core in the mounted condition of the vehicle wheelxe2x80x94allows optimal emergency rolling characteristics through the especially large outer diameter of the emergency rolling surface while retaining the optimal, small inner ring, diameter of the bead core for attaining good spring deflection of the tire and, thus, good comfort characteristics. The design of a vehicle wheelxe2x80x94in which the largest outer diameter of the emergency rolling surfaces amounts to a factor of between 1.1 and 1.2 greater than the inner ring, diameter of the bead core in the mounted condition of the vehicle wheelxe2x80x94represents an optimal design range of the standard tire dimensions for solving the conflicting goals of good emergency rolling characteristics on the one hand, and comfort and weight of the vehicle wheel on the other hand.
The design of a vehicle wheel, in which the bead core exhibits an expansibility and/or contractibility of 5% to 30%, enables a simple and reliable mounting, despite optimal emergency rolling characteristics through the formation of a particularly large outer diameter of the emergency support surfaces, despite retaining the design to attain good spring deflection of the tire and, thus, good comfort characteristics through an optimally small inner ring diameter of the bead core. Via simplexe2x80x94in particular elasticxe2x80x94expansion and/or contraction of the bead, the bead is adjusted, respectively, to the optimal diameter which is necessary for mounting or dismounting over the emergency support surfaces; to the required, optimal diameter for mounting or dismounting over the wheel flange that is oriented inward; and to the required, optimal diameter for the secure seating in the toroidal chamber. The design of a vehicle wheel, in which the bead core exhibits an expansibility and/or contractibility from 10% to 20%, enables a simple and reliable mounting, in the optimal manufacturing range of the standard tire dimensions for solving the conflicting goals of the emergency rolling characteristics on the one hand, and the comfort and weight of the vehicle wheel on the other hand.
The embodiment in which the bead core exhibits an expansibility of 5% to 30% and a contractibility of 1% to 5%, and in which the bead core is not expanded and not contracted, particularly in the mounted condition of the vehicle wheel. By simplexe2x80x94in particular elasticxe2x80x94expansion expansion from the condition in which it is not expanded and not contracted, the bead core is brought to the optimal, large diameter over the emergency support surface for mounting or dismounting. By simplexe2x80x94in particular elasticxe2x80x94contraction from the unexpanded and uncontracted state, the bead core is brought to the optimal, small diameter over the wheel flange, which is oriented inward, for mounting or dismounting. The embodiment of a vehicle wheel, in which the bead core exhibits an expansibility of 10% to 20% and a contractibility of 2.5% to 3.5% enables a simple and reliable mounting in an optimal manufacturing range of the standard tire dimensions for solving the conflicting goals of good emergency rolling characteristics on the one hand, and comfort and weight of the vehicle wheel on the other hand. It is particularly advantageous if the bead corexe2x80x94in the mounted state of the vehicle wheelxe2x80x94is not expanded and not contracted, and, thus, is generally free of inner forces exerting influence in the circumferential direction. Particularly advantageous is the elastically expandable and elastically contractible design. The bead core is expanded in the circumferential direction from the unexpanded and uncontracted condition for mounting over the emergency support surfaces in opposition to the elastic restoring forces. After the mounting over the emergency support surfaces, it is reduced again in its circumferential length by the restoring forces until it reaches the condition in which it is not expanded and not contracted. To mount over the wheel flange oriented inward, the bead core is contracted in the circumferential direction from the condition in which it is not expanded and not contracted, in opposition to the elastic restoring forces. After the mounting over the wheel flange, it is then again increased in size in its circumferential length in the toroidal chamber by the restoring forces back to its unexpanded and uncontracted state. The dismounting ensues in a corresponding manner.
Another embodiment makes possible a reliable, easily manageable embodiment of a filler ring. The rubber-coated stress supportsxe2x80x94of the multifilament or monofilament variationxe2x80x94, which are generally oriented in the circumferential direction and are constructed of steel or cloth, guarantee a secure, reliable retention of the seating of the filler ring on the bearing surface in the toroidal chamber and guarantee sufficient elasticity for axial mounting and dismounting. Particularly easy to manufacture is the embodiment of the filler ring from a continuous stress support which is helically spooled on the axis of the filler ring.